Great idea failed.

[90LX_Notch]

Problem: Position and drill tiny holes. (#79 and #80 size)

Solution: A Morse Taper #3 holder for a Dremel Flex Shaft running through the Mini Mill spindle.

Execution: Machined the holder on the money. Nice tight fit in the spindle. The Dremel Flex Shaft fits tight in the holder. Locks in nicely with a set screw. Mount up the Dremel Drill chuck. Insert a #79 bit. Now I have a nice high speed drill that I can accurately postion. Wrong!! The Flex Shaft has run out. So much, that I could use the end of the drill to tram the mill!

If I had only thought to check the Flex Shaft for runout before I made the holder. oh:

 

[rake60]

It sounded like a good idea in theory.

Someone once said:
"The only people who have never failed
are those who have never tried."

Never stop trying!

Rick

 

[bearcar1]

I'm sure that you have/are looking into ways to correct he run out, what steps need to be taken to do so?

BC1
Jim

 

[bentprop]

The flex shaft is really more of a sanding/grinding accessory.As such,runout is relatively unimportant.As you've found out,precision is not it's strong point. :-\
But remember,the only dumb question is the one that's never asked ;D

 

[90LX_Notch]

Rick- I'm not giving up. I have another idea cooking up in my head.

Jim- I'm not going to worry about it. If I can get my next idea to work I won't need it. (Completely switching direction.)

Bentprop- Exactly right. It's a Hobby / Craft tool not a machine tool. I had planned on it running more true. With .0145 dia. drill in there a few thou. run out is quite large. It would be like having a .500 dia drill wobble .125 or greater.

 

[stevehuckss396]

I have drawings for a spindle that will accept a er11 collet. If you can cut threads on the lathe you could make one and drive it with an rc motor or something.

 

[90LX_Notch]

Steve,

Actually, what I am thinking of doing, is to take the MT3 holder I made for this project. Counter bore it for bearings and make a spindle to accept the Dremel drill chuck. Then power the spindle with the Dremel through pulleys or a simple gear train. I like the RC motor idea better. Torque wise it should be much better then the Dremel.

Bob

 

[arnoldb]

Steve,

Actually, what I am thinking of doing, is to take the MT3 holder I made for this project. Counter bore it for bearings and make a spindle to accept the Dremel drill chuck. Then power the spindle with the Dremel through pulleys or a simple gear train. I like the RC motor idea better. Torque wise it should be much better then the Dremel.

Bob

Just a thought... You could make the spindle like you described, and just extend the shaft on the opposite side of the chuck so that you can use the Dremel flexible shaft to drive it. Then there's no need for pulleys/gears etc, and if you have a variable speed Dremel, you have speed control as well.

Regards, Arnold

 

[90LX_Notch]

Arnold,

The Flex Drive robs the Dremel of torque. I recently salvaged the gear train from a laser printer so I have gears on hand.

Bob

 

[arnoldb]

The Flex Drive robs the Dremel of torque. I recently salvaged the gear train from a laser printer so I have gears on hand.

That's true. The salvaged gear train would be the best option; there's some good stuff in discarded printers
Regards, Arnold

 

[lugnut]

The need for speed seems to be the answer for drilling small hole and of course the ability to hold the drill bit and keep it in line with the hole.
I just read a article on building a clamp or attachment to hold a dremel tool or router onto the quil of a milling machine and use the mills fine feed capabilities to feed the drill.
should work.
MEl

 

[Maryak]

Mel,

I have not tried your idea of a clamp to hold a dremel, but I have tried drilling using the quill fine feed with relatively small (1/8") drills. The problem I found was the complete lack of feel and not knowing if the bit was being over or under fed, also it was difficult to back off quickly and to clear the chips in a deeper hole.

May I suggest you try it and see what you think. ???

Best Regards
Bob

 

[lugnut]

I have drilled a lot of small holes with my mill. Well down to a #40, You have to remember it's not a big old honkern BP or some other 3 ton monster. IT is just a little X3 Mill/drill and the fine feed is very sensitive to the touch.
Mel

 

[Maryak]

I have drilled a lot of small holes with my mill. Well down to a #40, You have to remember it's not a big old honkern BP or some other 3 ton monster. IT is just a little X3 Mill/drill and the fine feed is very sensitive to the touch.
Mel

That's great Mel, seems like your clamp idea will work very well for you.

Best Regards
Bob

 

[Ed T]

In my past life we had occaision to drill lots of tiny holes. A few thoughts:
1) Small drills like high rotational speeds in order to create some velocity at the point you're trying to cut. If you think about the "tip velocity" on such a tiny drill you will realize that you have to turn it fast. We had, as I recall, some 60,000 rpm spindles. At these speeds, runout was a bad thing because the drills would fatigue quickly.
2) Small drills do not clear chips very well and they are most often broken from chip clogs. To avoid this, you have to peck the holes. That is, drill a little, retract the drill to clear the chips then do it again. Tedious, but not as tedious as trying to get the broken drill out of the hole.
3) Some small drills don't drill at all. Get a few so that if one is DOA you can keep going. There's no practical way to sharpen them in the home shop (that I know of).
4) I found it useful to "choke up" on the drill so that only the part of the drill needed to make the hole I was trying to make extended beyond the chuck jaws. Worked for me.
Good luck!!

 

[shred]

My heretofore unused set of drills #60-#80 got a workout building the little Jenny Wren engine. All the holes were in brass, but I drilled them on an 8x36 Millrite at 2000 RPM, so it can be done. ER-16 collet set, slow feed (used the knee to feed) and lots of pecking and blowing out the chips got me through. My Taig with a 10K RPM spindle would have been better for the task, but I wanted to see how bad it would be on the big mill.

I found a broken 1/16" bit ground to a point to be very handy for spotting the tiny holes before drilling them.